Liquid-cooled turbo-generator



Sept. 23, 1969 I E. WIEDMANN 3,469,126

LIQUID COOLED TURBO-GENERATOR Filed oct. 24, 1966 2 Sheets-Sheet 1INVENTOR.

Eugen WIecLemwnn WEB/V575 United States Patent 3,469,126 LIQUID-COOLEDTURBO-GENERATOR Eugen Wiedemann, Baden, Switzerland, assignor toAktiengesellschaft Brown, Boveri & Cie., Baden, Switzerland, ajoint-stock company Filed Oct. 24, 1966, Ser. No. 588,910 Claimspriority, application Switzerland, Oct. 29, 1965, 14,991/ 65 Int. Cl.H02k 9/20 US. Cl. 31054 9 Claims ABSTRACT OF THE DISCLOSURE Aturbo-generator includes a hollow cylinder of insulating materialinterposed between the rotor and stator elements. The insulatingcylinder is spaced radially from the surface of the rotor to establish arunning space in which the pressure is reduced to reduce the rotorsurface friction losses, and the inner surface of the insulatingcylinder is lined with a helical pipe extending between the oppositeends of the rotor for circulation of a liquid coolant in order to removeheat from the space resulting from rotor surface friction and eddycurrent losses.

This invention relates to turbo-generator machine construction and moreparticularly to an improved arrangement for effecting cooling ofmachines of the type.

It is known practice in turbo-generators to separate the rotor spacefrom the stator space by insertion of an insulation air gap cylinderbetween the rotor and stator to allow the rotor to run within the airgap cylinder in air or other gas at greatly reduced pressure. In thisway the surface friction losses can be reduced and the efficiency of themachine improved.

A certain disadvantage of the above-mentioned design, however, consistsin that practically no heat is removed through the air gap between rotorand stator. Consequently the eddy current losses resulting on the rotorsurface bring about an undue increase of the temperature within the airgap cylinder. To prevent this, the heat can be removed through coolingpipes installed in the vicinity of the surface of the rotor iron. This,however, is a measure which meets with structural difficulties and isnot efficient enough in the case of a very large machine.

The principal object of this invention now is to provide an improvedturbo-generator structure with directly cooled stator and rotor windingsand a rotor space separated from the stator space by an insulation airgap cylinder, where the temperature within the air gap cylinder ismaintained at a permissible value in a simple manner. According to theinvention, this is achieved in that at the inner side of the air gapcylinder cooling pipes are arranged through which a cooling liquid, inparticular water, circulates.

The invention will be now explained in more detail in relation to theaccompanying drawings wherein:

FIG. 1 is a view in longitudinal central section through aturbo-generator provided with squarely configured cooling pipes at theinner side of the insulation cylinder provided in the air gap betweenthe liquid cooled rotor and stator elements;

FIG. 2 is a fragmentary view in section showing the arrangement of thesquare cooling pipes in the vicinity of one end of the turbo-generator,the view being drawn to a larger scale for a better showing of thestructural details;

FIG. 3 is a fragmentary view in section showing a circular configurationfor the cooling pipes, also drawn to larger scale for detailing;

FIG. 4 is a fragmentary view in section showing an "ice elongatedrectangular configuration for the cooling pipes, also drawn to largerscale; and

FIG. 5 is a fragmentary view in section showing still anotherconfiguration for the cooling pipes, this being a modified rectangularcross section, one side of which has a semi-circular configuration.

With reference now to FIGS. 1 and 2, where for the sake of simplicityonly the parts required for comprehension of the invention are shown, 1denotes the liquid cooled stator and 2 the liquid cooled rotor of theturbogenerator. Between the stator 1 and the rotor 2, an insulation airgap cylinder 3 is inserted, which hermetically separates the rotor spacefrom the stator space. On the inner side of cylinder 3, which can bemade of any suitable insulating material, for instance a syntheticresin, cooling pipes are arranged which extend helically along thecylinder surface and can be partially embedded therein. For example,several pipes arranged in parallel can be used to establish a multiplehelix.

FIG. 1 illustrates a double helix of two pipes 4 and 4. To keep the eddycurrent losses as low as possible, the cooling pipes are made of a metalof low electric conductivity, e.g. non-magnetic steel.

Where the cooling pipes are arranged in a multiple helix, these can bemanifolded at opposite ends of the in sulating air gap cylinder 3. Thus,as illustrated in FIG. 1, the feed-in ends of the dual helical pipes 4,4 are manifolded into an annular, distribution chamber 5 at one end ofcylinder 3 and to which an inlet pipe 5' is connected to supply theliquid coolant. Similarly, the discharge ends of the pipes 4, 4 at theopposite end of the insulation cylinder 3 are manifolded into anotherannular, collection chamber 6 at that end from which the liquid coolantis removed by a pipe 6'. If desired, the liquid coolant which gains heatby flowing through the helical pipe system 4, 4 can be re-cooled afterremoval and then recycled through the pipes.

FIGS. 3, 4 and 5 show other suitable cross-sectional configurations forthe piping used in conjunction with the inner wall of the annularinsulating air gap cylinder 3. Thus, in FIG. 3, the piping 4a is seen tobe of circular cross-section; in FIG. 4, the piping 4b has an elongatedrectangular cross-section; and in FIG. 5, the piping 4c has a modifiedrectangular cross-section, three of the sides of the pipe being straightand the fourth side being a semicircle.

Cooling of the stator and rotor elements of the turbogenerator isaccomplished by conventional constructions. The stator winding 7 iscompoosed of hollow conductors, for example, through which a liquidcoolant such as water is circulated, the water being admitted to theconductors through an inlet pipe 8 and removed for re-cooling andre-oirculation by means of an outlet pipe 9. Cooling of the rotorelement is likewise effected by circulating a fluid coolant such aswater in heat-transfer relation with the rotor conductors, theconductors being tubular for example for passage of the coolanttherethrough. The details for the rotor cooling have not been included.However the cooling water is introduced to one end of tthe tubular rotorwindings through a duct arrangement including a central bore in therotor shaft 10 and is removed at the same shaft end from the other endof the windings by means including an annular channel concentric withthe feed-in bore. Further details of one suitable arrangement forcooling the rotor conductors are disclosed in my copending applicationSer. No. 539,058, filed Mar. 31, 1966.

The rotor space 11 inside the air gap cylinder 3 is connected to avacuum pump VP, which produces there the required negative pressure orvacuum.

With the described arrangement, the friction losses of the rotor, aswell as a part of the eddy current losses resulting on the rotor surfaceare removed in simple manner through the cooling pipes in the stationaryinsulation air gap cylinder. At the same time there result theadditional advantages that the cooling pipes thus arranged not onlyprotect the air gap cylinder, which consists of a synthetic insulationresin, against excessive temperatures but also serve to mechanicallyreinforce it against the higher external pressure and also assure abetter stablity as to form. Furthermore, by using a helical arrangementof the cooling pipes with a coil of 360 or a multiple thereof zerovoltage is induced in all pipes, so that at the beginning and end theycan be connected metallically to a common water chamber for each.

I claim:

1. In a turbo-generator structure the combination comprising a statorelement, a rotor element spaced radially inward from said stator elementto establish an annular gap therebetween, a hollow cylinder ofinsulating material interposed in said annular gap and which extendsbetween the opposite ends of said rotor and stator elements, said hollowcylinder being spaced radially from the surface of said rotor toestablish therebetween a running space for said rotor, meansestablishing a reduced pressure condition in said space to decreasesurface friction losses, pipe means applied to the inner surface of saidhollow cylinder, and means for circulating a liquid coolant through saidpipe means thereby to effect removal of heat from said space resultingfrom rotor surface friction and eddy current losses.

2. A turbo-generator structure as defined in claim 1 wherein said pipemeans applied to the inner surface of said hollow cylinder extend fromone end of said cylinder to the other in the form of a helix.

3. A turbo-generator structure as defined in claim 2 wherein said pipemeans are arranged as multiple helices.

4. A turbo-generator structure as defined in claim 1 wherein said pipemeans consist of non-magnetic metal having a low electricalconductivity.

5. A turbo-generator structure as defined in claim 1 wherein said pipemeans is partially embedded in the inner surface portion of said hollowcylinder.

6. A turbo-generator structure as defined in claim 1 wherein said hollowcylinder is made from a synthetic resin and said pipe means is partiallyembedded in the inner surface portion thereof.

7. A turbo-generator structure as defined in claim 1 wherein said pipemeans is constituted as a helix extending between opposite ends of saidhollow cylinder and is made from a non-magnetc metal having a 10welectrical conductivity, said hollow cylinder being made from asynthetic resin and said helical pipe means being partially embedded inthe inner surface thereof.

8. A turbo-generator structure as defined in claim 7 and wherein in-flowand out-flow manifolds are provided at the opposite ends of said hollowcylinder and connected to the corresponding ends of said helical pipemeans.

9. A turbo-generator structure as defined in claim 1 wherein saidhelical cooling pipe is arranged with a coil of 360 or a multiplethereof.

References Cited UNITED STATES PATENTS 1,382,878 6/1921 Alexanderson310-54 1,494,715 5/1924 Schroeder "310-54 2,929,943 3/1960 Richardson31o 54 3,249,775 5/1966 Baylac 310-54 FOREIGN PATENTS 1,068,803 11/1959Germany.

ORIS L. RADER, Primary Examiner A. G. COLLINS, Assistant Examiner

